Prior work has shown that large amounts of anionic surfactants and soaps are absorbed and retained by fabrics, such as wool, cotton, dacron-cotton mixture and other fabric mixtures, skin and other similar substrates during the washing process. These residual surfactants and soaps are difficult to rinse from wool and skin. The removal of said residues from the skin is addressed in a copending cleanser composition filed of even date. Consumers perceive these residues left on clothes as a negative, since they change the way fabrics feel, and can possibly be irritating. Accordingly, the presence of residual anionic surfactant on clothes being perceived in a negative way by the consumer, and as a potential source of skin irritation, there is clearly a need to develop a fabric rinse product addressing this problem. A unique combination of a buffered organic acid and a nonionic surfactant has been shown to be very effective at removing residual soap from said fabrics.
It has been found that this fabric rinse reduced the levels of residual anionic surfactant retained by wool fabric after washing, by 40-60% compared to a water rinse. The amount of surfactant rinsed out of the fabric by the prototype was significantly greater than formulas containing either ingredient alone.
A study using wool fabric and laurate soap demonstrated that Ca++ and Mg++ salts that produce water hardness increase surfactant deposition and absorption of the soap to the wool fabric, a keratin substrate. Hence, the water hardness increases the binding of the laurate soap to wool and, by analogy to skin, decreases the ability to wash the soap off the wool or skin, which binds the soap surfactant in a manner similarly to wool. It is the removal of this soap and/or synthetic anionic surfactant residue from the washed and water rinsed fabrics such as wool that is the subject matter of present invention.
Commercial facial detergent compositions containing soap and assorted mixtures of surfactants for use in the wash cycle of the laundering operation has addressed the problem of fabric softness in the prior art by adding softening agents to the detergent composition; or by separately adding the softening agent in the rinse cycle of the laundering operation. However, the removal of soap and/or surfactant residue after washing fabrics with soap has not been addressed in the prior art.
The use of a nonionic surfactant as one of the ingredients in a liquid detergent for cleaning fabrics is well known in the prior art as disclosed in U.S. Pat. Nos. 3,764,544 wherein is disclosed a spot remover for wearing apparel containing a nonionic surfactant; 3,959,163 wherein is disclosed a stain removing composition containing a bleaching compound and a nonionic surfactant; and 4,206,070 wherein is disclosed a binary surfactant system of nonionics.
U.S. Pat. No. 3,915,633 discloses an aqueous prewash aerosol spray soil release composition for use with a detergent or soap in a laundering operation, consisting of 1-20% by weight of an organic acid, i.e. citric acid, 2-30% by weight of an anionic or nonionic surfactant, water and an aerosol propellant. Canadian Pat. No. 1,086,178 discloses a liquid heavy duty laundry detergent composition containing 20-70% by weight of a soluble ethoxylated nonionic surfactant, 0.1-1.25% by weight of a polyacid, i.e. citric acid, and water/organic solvents, having a pH of 6-7.5.
Also disclosed in the prior art are mixtures of a nonionic surfactant and polyacrylate thickeners in aqueous dishwashing detergent formulations as disclosed in U.S. Pat. Nos. 3,950,260 and 4,226,736.
U.S. Pat. No. 4,501,680 discloses acidic liquid detergent compositions for cleaning ceramic tiles without eroding grout between them, comprising a minor proportion of glutaric acid and a lesser amount of phosphoric acid to provide a pH of 3-5, a minor amount of an ethoxylated fatty alcohol, a minor amount of a diethylene glycol monoalkyl ether, and a major amount of water.
U.S. Pat. No. 4,172,140 discloses an antimicrobial composition for inhibiting the growth of microorganisms in an aqueous fluid medium comprising as the active ingredients, an admixture of 1,3-dimethylol-5,5 dimethyl hydantoin and disodium ethylene diaminetetraacetate, for use in metal working fluids, cutting oil fluids, coolants, lubricants, and the like.
U.S. Pat. No. 4,612,137 discloses an anti-yellowing detergent composition comprising citric acid or salt and isocitric acid or salt and a surfactant, which may be anionic, nonionic, etc.
None of the aforesaid prior art disclose a fabric rinse to remove residual soap and/or synthetic anionic surfactants absorbed by the fabric during the washing process, consisting of a low level of a nonionic surfactant as the sole surfactant, a minor amount of an organic acid (or salt thereof) having a pKa from 4.5 to 6.5 to provide a pH of about 4.5 to 6.5, and a major amount of water, which may be thickened with polyethylene glycol - 150 distearate to a thick liquid or thickened with an acrylic acid polymer to form a gel, and preferably contains a preservative system.